PSL300H1 Final: PSL300 Final Exam Review
PSL300
Final Exam Review
Lecture 1:
Physiology
- The science of how the body functions. It spans from molecules to organisms. Molecules -> cells
-> tissues -> organs -> organ systems -> Organisms -> populations of organisms
Homeostasis
- The process of maintaining a constant internal environment despite changing conditions. Claude
Bernard 1880s: The osta of the iteal eioet. Cao s: ‘egulatio of
internal environment
Local Control
- Change in immediate vicinity
- Paracrine or Autocrine
Reflex Control
- Coordination of the reaction lies outside the organ that carries out the response
- Nervous system, endocrine system, or both
Positive Feedback
- An initial stimulus leads to a response, producing the same stimulus, looping back to the
response. An outside factor stops the loop via feedback
Negative Feedback
- Initial stimulus leads to a response, cause an increase or decrease in stimulus
- Much more common than positive feedback
Feed forward
- Anticipatory response (i.e. salivation, anticipate food)
Blood Pressure regulation
- When blood pressure is low, sensory receptors in the aortic and carotid sinuses sense it
- The signal goes to the regulatory center in the brain
- The arterial wall constricts
- Reversal, BP rises
- Constricting arterial walls results in an increase in blood pressure
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Oxytocin and uterine contractions
- Baby pressed against cervix, causing uterine stretch
- Oxytocin release, uterine contractions, causing the baby to press against cervix more
- Loop ends when the baby drops
Feedback control
- Stimulus → receptor/sensor, afferent pathway → Integrating center → efferent pathway →
Target of effector → response
- Afferent = going towards something (no afferent in endocrine reflex)
- Efferent = going away from something
- Effector = target
- Afferent = information towards brain
- Efferent = information away from brain
Biological Rhythms
- Result from changes in a set point, i.e. body temperature drops at night, raises towards noon,
drops at night
- Cortisol increases in morning, peaks at noon, lowest at night
Endocrine Systems
- No response unless the cell has a receptor on it
Maintaining homeostasis and other body functions requires intracellular communications
a) Gap Junctions: i.e. for Calcium, ATP, found in heart, kidney, direct cytoplasmic transfer
b) Contact dependant Junctions: membrane protein interactions, requires Cell Adhesion
Molecules, which act as receptors, linked to cytoskeleton, intracellular enzymes
c) Autocrine signals : same cell
d) Perecrine: activated on one cell, diffuses out, example: histamine, released upon injury
Where are hormones produced?
Primary endocrine organs
- Pineal gland, hypothalamus, pituitary gland, thyroid gland, parathyroid glands, thymus, adrenal
gland, pancreas, ovaries, testes, placenta
Secondary
- Heart, stomach, liver, kidney, small intestine, skin, adipose tissues
Nervous system
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- Localized/specific effect
- 1) Neurotransmitters are chemicals secreted by neurons that diffuse across a gap to the target
- 2) Neurohormones: released into the blood for action by different targets
- 3) Neuromodulators: neurocrine that acts slowly as paracrine or Autocrine signal
Systems:
- Exocrine system Into a duct
- Endocrine: into the blood
How were early hormones identified?
- Remove gland, check effect
- Replace gland/extract
- Implant gland/extract to create excess, observe effect
- Purify extract and test for effect in biological assay
Lecture 2: Classification of Hormones and control of release
221-232
Hormone Features:
- Can be made in different parts of body i.e. somatostatin made in hypothalamus and pancreas
- Chemicals made by cells in specific endocrine glands of other tissues
- Transported in blood to distant target
- Binds to specific receptors
- May act on many tissues
- Alter activity of target cells
- Action must be terminated
- Maintain homeostasis or precipitate change in many physiological processes
Posterior Pituitary
- Secretes vasopressin and oxytocin
Anterior Pituitary
- Secretes prolactin, TSH, ACTH, GH, FSH, LH
- Hormones stored in vesicles, brought from hypothalamus to the pituitary
Singe preprohormone can contain several copies of the same gene
- Splitting of PPH gives a hormone, other peptides and a signal sequence
- Can give more than one type of hormones
- Synthesis of peptide hormone:
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Document Summary
> tissues -> organs -> organ systems -> organisms -> populations of organisms. The process of maintaining a constant internal environment despite changing conditions. Bernard 1880s: (cid:862)the (cid:272)o(cid:374)sta(cid:374)(cid:272)(cid:455) of the i(cid:374)te(cid:396)(cid:374)al e(cid:374)(cid:448)i(cid:396)o(cid:374)(cid:373)e(cid:374)t. ca(cid:374)(cid:374)o(cid:374) (cid:1005)(cid:1013)(cid:1006)(cid:1004)(cid:859)s: egulatio(cid:374) of internal environment. Coordination of the reaction lies outside the organ that carries out the response. An initial stimulus leads to a response, producing the same stimulus, looping back to the response. An outside factor stops the loop via feedback. Initial stimulus leads to a response, cause an increase or decrease in stimulus. The signal goes to the regulatory center in the brain. When blood pressure is low, sensory receptors in the aortic and carotid sinuses sense it. Constricting arterial walls results in an increase in blood pressure. Baby pressed against cervix, causing uterine stretch. Oxytocin release, uterine contractions, causing the baby to press against cervix more. Stimulus receptor/sensor, afferent pathway integrating center efferent pathway .
